(1) FIELD OF THE INVENTION
The present invention relates to a keyboard operated by hand and used for a piano and an electronic musical instrument.
(2) DESCRIPTION OF THE PRIOR ART
The natural scale is composed of the natural tones C, D, E, F, G, A, and B, and the musical interval is different from each of adjacent tones. Half tone interval is provided between the tones E and F, and between the tones B and C, whole tone interval is provided between remaining tones adjacent to each other. Therefore, it is difficult to realize a keyboard for musical instrument to be operated by hand, in which it is easy to play the natural tones and to achieve an easy transposition.
U.S. Pat. No. 4,782,734 shows a standard keyboard in which the interval between the front white keys (natural tone keys) is different from the interval between the musical intervals, and therefore the transposition becomes difficult.
At the rear portion, the white keys are in a lower position than the rear back keys (derivative tone keys), and therefore the white keys are difficult for playing.
U.S. Pat. No. 4,444,083 shows the keyboard such arrangement that each width of the white keys E, F, B, and C is set to be 3/4 as that of the white keys D, G, and A, thereby approaching the distance between the white keys to the musical interval. However, the operation to press the front white key or the rear black key is varied in each transposition, the operation of fingers undesirably becomes irregular thereby making difficult the transposition.
U.S. Pat. No. 4,658,696 shows an embodiment having musical scale arrangement of a pedal keyboard in which each key of natural tones is located at higher position than each of the keys sandwiched between two adjacent natural tone keys to form a valley, and therefore the natural tones are comfortable to play. However, since the natural tones are arranged, in equidistance, by sandwiching the valley, the interval of the natural tone keys do not conform with the interval of musical interval. Therefore, it is difficult to enable the transposition with the same operation of foot.
U.S. Pat. No. 3,392,620 shows an arrangement of keyboard that the front keys and the rear high keys are arranged in the interval of whole tone (two times of half tone), and therefore it is easy to enable the transposition with the same operation of finger, for each whole tone. However, since the natural tones are positioned at the front and the rear positions, it is difficult to detect the natural tones thereby hardly playing them. (It is the same as U.S. Pat. No. 3,468,209 in this point of view.)
U.S. Pat. No. 3,433,881 shows a chromatic keyboard for pedal arranged such that the interval of each key is set to the half tone interval in order to make easy the transposition. However, it is difficult to detect the natural tones thereby hardly playing them.